Tetracarbonyl 2-isocyano-l,3-dimethylbenzene iron

Stirrer-heater. Heating is continued at until CO evolution ceases, generaUy requiring between IS and 30 min. It is important to stop heating the reaction mixture as soon as the reaction is complete. Otherwise, a darkening occurs that imparts an undesirable color to the product. Purification to remove this discoloration has proved to be difficult.  

The reaction mixture is cooled to room temperature and the solvent and excess Fe(CO)5 are removed under vacuum. The product is obtained as a yellow, crystalUne solid. Yidd 8.6 g (96%). This material is sufficiently pure for most purposes, but it may be recrystallized from pentane. 

The same equipment is used as described in the procedure in Section B. The flask is charged with Fe(CO)4(CNC6H3Me2-l,3X1.79 g, 6.0 mmol), CoCl2 2H20 (0.034 g, 0.2 mmol), and toluene (30 mL), and the mixture is heated to 85 C with stirring. To the hot solution is added 2-isocyano-l,3-dimethylbenzene (1.57 g, 12.0 mmol). It is crucial to add the isocyanide to the hot solution. Otherwise, catalyst deactivation (believed to be due to isocyanide polymerization) occurs. This results in a sluggish and incomplete reaction.  

The compounds Fe(CO)5, XCNC4H3Me2-l,3), (n = 1-5) are characterized by IR vibrational spectroscopy (voo and Vnc 1800-2200-an region) and by NMR spectroscopy (aromatic and methyl protons). Selected spectroscopic data for these complexes are given in the Table L Infrared spectroscopy may conveniently be used for the monitoring of the progress of the substitution reaction, and NMR spectroscopy for an estimate of product purity. The complexes may also be characterized by mass spectrometry 

Gladkowski and F. R. Scholer, Abstracts of Papers from the Centennial American Chemical Society Meeting, New York, 1976, INOR 133. 

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